IS 14900 : 2018Transparent Float Glass

IS 14900:2018 is the specification for transparent float glass — the basic flat glass (made by the float process) used for building glazing, and the substrate from which toughened, laminated, insulated and coated safety/architectural glasses are made. It is the product code behind the glazing line item and the base for all processed-glass specifications.

It is read with the glazing stack:

• IS 2553 Part 1 — safety glass (toughened/laminated — what float glass is processed into for safety applications)
• NBC 2016 Part 6 — building finishes / glazing (where safety glass is *mandatory*) · IS 875 Part 3 — wind on glazing
• IS 3548 — glazing & joinery workmanship · IS 16231 — energy-efficient glazing references

IS 14900 fixes the quality of basic transparent float glass:

• Nominal thickness & tolerance (e.g. 4 / 5 / 6 / 8 / 10 / 12 mm …) — thickness is the primary structural parameter against wind load
• Optical quality — freedom from distortion, bubbles, inclusions, scratches, ream within defined limits
• Dimensions, edge & flatness tolerances
• Visible-light transmission for clear float

The critical limitation: plain float glass is annealed — it is NOT safety glass. It breaks into large, sharp, dangerous shards. NBC Part 6 *mandates safety glass* (toughened to IS 2553, or laminated) in impact-risk and overhead/critical locations — doors, side panels, low-level glazing, balustrades, overhead glazing, large panes, wet areas. IS 14900 float glass is the substrate; it must be processed (toughened/laminated) to a safety standard for those locations — specifying plain float glass there is a code violation and a serious injury risk.

Structurally, the glass thickness must also be checked against the design wind load (IS 875 Part 3) for the pane size — large panes need thicker (and often toughened/laminated) glass.

Scenario: glazing for a building façade including a glass door, a large window pane, and a balustrade.

Step 1 — base spec: transparent float glass to IS 14900 of the required optical quality and nominal thickness.

Step 2 — wind/structural: for each pane size, check the thickness against the design wind pressure (IS 875 Part 3) — large panes need greater thickness (and usually toughening) to limit deflection/breakage.

Step 3 — safety processing (mandatory): the door, side panels, low-level window and balustrade are impact/overhead-risk locations → NBC Part 6 requires safety glass: toughened to IS 2553 (breaks into small blunt fragments) or laminated (fragments retained) — plain IS 14900 float glass is *not permitted* there.

Step 4 — performance glass (if specified): energy/solar — coated/insulated units built on the float substrate.

Step 5 — accept & glaze: verify IS 14900 thickness/optical quality of the base glass and the IS 2553 certification of the processed safety glass; glaze per IS 3548 with proper edge clearance/gaskets (edge damage initiates breakage).

1. Using plain float glass where safety glass is mandatory. Doors, low-level/side panels, balustrades, overhead and large panes need toughened/laminated safety glass per NBC Part 6 — annealed float glass there is a code violation and a laceration hazard.

2. No wind/thickness check. Glass thickness must suit the pane size and design wind (IS 875 Part 3); large thin panes deflect excessively and break.

3. Confusing float with toughened. Float is the *substrate*; toughening/lamination (IS 2553) is a separate process with its own certification — they are not interchangeable.

4. Edge damage / poor glazing. Glass breaks from edge flaws; nipped, un-gasketed or zero-clearance glazing initiates failure regardless of glass quality.

5. Accepting on appearance. Verify IS 14900 thickness/optical quality and, for safety locations, the IS 2553 processed-glass certification — not just 'clear glass'.

• IS 2553 Part 1 — safety glass (toughened / laminated)
• NBC 2016 Part 6 — building finishes / mandatory safety-glass locations
• IS 875 Part 3 — wind loads on glazing/cladding
• IS 3548 — code of practice for glazing & joinery workmanship
• IS 16231 / IS 2835 — energy-efficient / sheet glass references

IS 14900:2018 is a current revision and is the base spec for architectural glass, but the **single most important practitioner point is what it is *not*: float glass is annealed, not safety glass.** The recurring, serious failure is plain float glass installed in doors, low-level panels, balustrades or overhead glazing — locations where NBC Part 6 *mandates* toughened (IS 2553) or laminated safety glass — leading to dangerous shard injuries. Float glass is the *substrate*; the safety performance comes from processing it to IS 2553.

The practitioner contract: specify IS 14900 float for the base quality/thickness, check thickness against the design wind for each pane size, and mandate IS 2553 toughened/laminated safety glass for every impact-risk and overhead location per NBC Part 6 — accepting the safety-glass certification, not just the float. Detail the glazing (edge clearance, gaskets, no edge damage) per IS 3548. The expensive/dangerous lesson is always the same: 'clear glass' specified without the safety-processing where the code requires it.